1. Field of the Invention
The present invention relates to systems and methods for transmitting media programs and other data to subscribers, and in particular to a system and method for providing a auxiliary data broadcasting service.
2. Description of Related Art
Television, audio, and other media programs can be distributed to viewers by a variety of broadcasting methods. These methods include traditional analog broadcast television, the upcoming digital broadcast television, cable television (both analog and digital), satellite broadcasting (both analog and digital), as well as other methods. These methods allow channels to be multiplexed and transmitted over a common transmission medium.
Advances in data compression techniques, including those developed by the joint photographic experts group (JPEG), the motion pictures experts group (MPEG), and others, have permitted more and more data to be broadcast without increasing the bandwidth of the broadcast link. JPEG is an ISO/ITU standard for compressing still images that uses discrete cosine transform (DCT). JPEG provides lossy compression with ratios up to 100:1 and higher. Depending on the image complexity, ratios of 10:1 to 20:1 often provide little or no noticeable loss in image quality. Compression is achieved by dividing the picture into tiny pixel blocks, which are halved over and over until the ratio is achieved. MPEG uses the same intraframe coding as JPEG for individual frames, but also uses interframe coding, which further compresses the video data by encoding only the differences between periodic key frames, known as I-frames.
In recent years, techniques have been developed which allow auxiliary data to be embedded into such media programs without materially affecting the perceived quality of the received media program. One such technique, referred to as steganography, is well known, and is described in the following patents, which are hereby incorporated by reference: U.S. Pat. No. 5,727,092, issued Mar. 10, 1998 to Maxwell T. Sandford II et al. for “Compression Embedding”; U.S. Pat. No. 5,778,102, issued Jul. 7, 1998 to Maxwell T. Sandford II et al. for “Compression Embedding”; and U.S. Pat. No. 5,659,726, issued Aug. 19, 1997 to Maxwell T. Sandford II et al. for “Data Embedding.”
While steganographic techniques are useful, they are not as widely applied as their advantages would suggest. One difficulty with the application of steganographic techniques revolves around conflicts between the ownership and control of the media programs, the auxiliary data to be embedded, and the broadcast channels used to transmit the data. Media program providers are often reluctant to allow data of unknown or uncontrolled origin to be embedded into media programs. This is due to fears of degraded picture quality and exposure to liability for the embedded data. At the same time, auxiliary data providers are often reluctant to allow their data to be broadcast by media program providers, and do not have the infrastructure required to indicate to their subscribers when the data will be received. Further, the auxiliary data provided by third parties may include time-sensitive information, which must be provided with a minimum latency or according to a minimum guaranteed quality of service level (QoS). What is needed is a system and method that provides a brokering service between media program providers, broadcasters, and auxiliary data providers. The present invention satisfies that need.